A normal day on facebook.

if you used that money to buy food for everybody the price would go up exponentially due to the laws of supply and demand. The government subsidy for food would way heavily on the taxpayer who would see no return other than his taxes and the price of food go up. Eventually those that are given the food would become dependent on it and others that have food, but very little, would also want the free food, which would further increase the price.

As you can see, this is no economically feasible.